A card structure, such as a house of cards or card tower, is made using planar stackable members such as playing cards, business cards, index cards, recipe cards or the like. These card structures are built using a method that relies on nothing more than balance and friction in order to stay upright. Ideally, adhesives or other external connecting methods are not used, and no damage or alterations are made to the planar stackable members themselves. The larger the card structure, the more likely it is to fall due to the higher number of balanced planar stackable members that could fail and compromise the integrity of the card structure. Important to the structural integrity of the card structure are the first few cards, known in the art as the “cell” or “pipe column”, which provides the foundation for the structure. Beginners have traditionally experienced difficulties in balancing the first few planar stackable members to build the cell of the structure. Accordingly, there is a need in the art for a grooved supporting member that will assist a person in the construction of a card structure by providing support for the cell of the structure.